PHYSICS [3 Mark Question Answer]

Simple Machines and their examples are as follows:

1. The lever: Examples are a crowbar, claw hammer, a pair of pliers, etc.
2. The Inclined plane: Examples are ramp, staircase, hilly roads, etc.
3. The wedge: Examples are knife, axe, plough, nail, etc.
4. Screw: Examples are A screw.
5. The wheel and axle: Examples are steering wheel of a car, bicycle pedal, etc.
6. The pulley: Examples are a pulley used in raising a load.

A wedge is a double inclined plane such that the two sloping surfaces taper to form either a sharp edge or a pointed edge.
Examples: A knife, an ax, a chisel.
In some special cases, the number of inclined planes used can be more than two as well. In such cases, the sloping surfaces generally taper to form either a very sharp or a pointed edge to split or pierce materials. Pins, nails, and needles are examples of pointed wedges. The front end of a boat is shaped like a wedge so that it can easily cut across the flowing water.
The wedge works on a principle of an inclined plane.

The mechanical advantage of an inclined plane is the ratio of the length of the plank to the vertical height of the load raised. Its value is greater than one. Therefore, an inclined plane acts as a force multiplier. Thus, it can be used to lift heavy loads.
Example: If a heavy box needs to be loaded on a lorry, it is far easier to push it over an inclined plane than to lift it up. Steeper the inclined plane, greater will be the effort required to push up the load.
Sloping ramps, flyovers, roads on hills and staircases are all examples of inclined planes.

To raise a load, the load is attached to one end of the string and the effort is applied at the other end by pulling it is a downward direction . as shown in fig.

In an actual pulley due to friction, the mechanical advantage is less than 1 (i.e. the effort is more than the load).
The reason for using the pulley when its mechanical advantage is equal to 1 or less than 1 is that the pulley allows us to apply the effort downwards i.e. in a convenient direction. To raise a load directly upwards is difficult. But with the help of a pulley, the effort can be applied in the downward direction to move the load upwards. One can hang on it to make use of his own weight also in order to apply the effort.

The mechanical advantage of an inclined plane is the ratio of the length of the plank to the vertical height of the load raised. Its value is greater than one. Therefore, an inclined plane acts as a force multiplier. Thus, it can be used to lift heavy loads.
Example: If a heavy box needs to be loaded on a lorry, it is far easier to push it over an inclined plane than to lift it up. Steeper the inclined plane, greater will be the effort required to push up the load.
Sloping ramps, flyovers, roads on hills and staircases are all examples of inclined planes.

A wedge is a double inclined plane such that the two sloping surfaces taper to form either a sharp edge or a pointed edge. Examples: A knife, an ax, a chisel.
In some special cases, the number of inclined planes used can be more than two as well. In such cases, the sloping surfaces generally taper to form either a very’ shaip or a pointed edge to split or pierce materials. Pins, nails, and needles are examples of pointed wedges. The front end of a boat is shaped like a wedge so that it can easily cut across the flowing water.
The wedge works on a principle of an inclined plane.

Taking care of machines: Some of the ways in which machines should be cared for are given below.

1. Machines should be kept in a clean environment, which is free from dust and moisture.
2. When not in use, machines should be kept covered to prevent the collection of dust on them.
3. Machines made of iron should be protected from rust by coating them with paint.
4. The moving parts of a machine should be regularly oiled with good-quality machine oil to reduce friction and wear and tear.

In Class I levers (also called levers of first order), the fulcrum lies between the load and the effort, i.e., the load and the effort are on the opposite sides of the fulcrum.
Examples: See-saw, pairs of scissors, pliers, beam balance, etc.
The mechanical advantage of a Class I lever is always greater than one. These levers act as force multipliers.